This application claims priority from Japanese Patent Application No. 2003-286008, filed Aug. 24, 2003, the entire disclosure of which is incorporated herein by reference.
1. Technical Field of the Invention
The present invention relates to a plate rolling mill that presses down a plate material between work rolls.
2. Description of the Related Art
With a plate rolling mill that presses down a plate material between a pair of work rolls that hold the material, the lateral distribution of the thickness of the material rolled is required to be controlled to have a convex or concave section, thereby having a predetermined plate crown, even under varied conditions.
Patent literature 1 has already been disclosed and Patent literature 2 (not published yet) has been applied to control a plate crown such as that described above.
The “rolling mill” of Patent literature 1 is shown in FIG. 1; a pair of rolls 51 with roll crowns having diameters that vary over the entire lengths of the roll barrels are disposed, wherein
the aforementioned roll crowns are formed to make both roll barrel profiles convex, and their maximum-diameter portions 53 are shifted from the width-wise centerlines 52 of both rolls, in the axial directions of the rolls; that is, each shape of the rolls is located asymmetrically about the axis 52; in addition, the above-mentioned rolls are configured to be movable in the axial direction thereof.
In “Mill rolls and mill using them” of Patent literature 2 shown in FIG. 2, mill rolls (in this example, intermediate rolls 63) are formed with four shaped-portion ranges; i.e., an extension barrel portion A composed mainly of a small-diameter portion that does not contact reinforcement roll 64 at any shift location, a cylinder roll portion B that is in contact with the reinforcement roll, a decrement portion C, whose diameter gradually decreases from the end of the cylinder roll portion, and an increment portion D, whose diameter gradually increases from the end of the decrement portion. The shapes of these portions A, B,C and D are expressed by a sixtic-functional curve defined by 7 points, from one end to the other of a roll axis. In FIG. 2, 62 represents the work rolls.
[Patent Literature 1]
Japanese Patent Publication No. 5-13726, 1993
[Patent Literature 2]
Specification of Japanese Patent Application No. 259629, 2002 “Mill rolls and mill using them,” not published yet
The mill of Patent literature 1 presents rolls that cannot be easily shifted during a rolling operation, because the rolls receive a rolling load.
A problem with the mill of Patent literature 2 is that the shapes of intermediate shift rolls are not effective for forming a plate crown into the concavity shown in FIG. 3B because the intermediate shift roll is concave, although the rolls can effectively form the convex plate crown shown in FIG. 3A.